Control system for burners producing high temperature flames



June 4, 1935. G. D. BowER CONTROL SYSTEM FOR BURNERS PRODUCING HIGH TEMPERATURE FLAMES Filed April l0, 1933 INVENTOR GEORGE BOWER BY @1M/ft ATTORNEYS Patented June 4, 1935 UNITED STATES COTROL SYSTEM FOB BUBNEBS PBODUC- ING HIGH TELIPEBATUBE FLAMES George D. Bower, Columbia Heights, Minn., as-

signor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware applicati@ April 1o, 1933, serial No. 665,462

' -12 claims. (ci. 15s-2s) The present invention relates broadly to the use of the flame produced by av burner as part of an electrical conducting system. Such an electrical conducting system may.be used for 5 any desired purpose but has particular utility in safety mechanisms whereby the supply of fuel to a-burner is` controlled in accordance with the condition of the `llame produced by the burner.

It has been proposed', heretofore, to use the conductivity of the flamel produced by a pilot burner to prevent operation of the main burner if the pilot burner should become extinguished or .to use the ilame produced by a main burner to permit continued operation of the main burner as long as ame is being produced thereby. Such prior art systems have generally included an electronic device, known as a grid glow tube, the grid of which has been connected to the flame of the burner whereby the grid is grounded when llame is presen-t, thereby allowing current to flow from the cathode to the anode of the grid glow tube to permit continued operation of the burner. rlhe grid of the grid glow tube -has been connected to the flame of the burner by placing an electrode in the path of the ilame and connecting the electrode to the grid.

Constructions of the above type have proven quite satisfactory when the flame into which the electrode projects does not develop too high a temperature but have been found to be sadly wanting in several respects when the electrode projects, for instance, into the high temperature ilame produced byia large oil burner.

When the average electrode is placed in the high temperature ilame produced by a large oil burner, the electrode becomes heated to such an extent that it becomes soft and bends, by its own weight, out of the path of the flame, thereby rendering the apparatus inoperative. It is possible to nd an electrode material which will not soften sufficiently to bend under its own weight when heated by ahigh temperature flame but additional diniculties have been encountered when the electrode is` placed in a high temperatemperatures withoutA bending under its own `stitute a part of a safety mechanism for the weight. In addition, this deposit of carbon on the electrode, if the electrode does not bend out of the path of the flame, may cause the llame to be disrupted in a very undesirable manner.

In order to overcome these diiliculties which arise from placing an electrode in a burner flame, particularly the high temperature iiame of a large oil burner, the present invention places the electrode in an auxiliary flame, such as a gas flame which may well be the ignition means for the main ilame, the auxiliary flame in turn contacting with or projecting into the main ilame. In this manner electrical current is transmitted from the electrode to the main name through the auxiliary flame. The auxiliary ilame has a much lower temperature than the main flame so the electrode does not become heated to such a high degree as it would were it placed directly in the path of the main flame. Where the auxiliary flame is a gas flame, there is practically no carbonization of the electrode whereby theevils above pointed out in connection with the placing of the electrode in the main name are circumvented.

One of the primary objects of the present invention, therefore, is the provision of an electrical conducting systemwhich includes an electrode, a main flame, (generally `a high temperature flame) and an auxiliary ilame which directly electrically'connects the electrode and main flame. The auxiliary flame is generally of a considerably lower temperature than the main ame.

'This electrical conducting system may conmain burner and is preferably used to control a sensitive relay of any desired type. The sensitive relay may take the form of any suitable electronic device. Specifically any type of grid controlled rectiiler, such as the well-known grid glow tube, is particularly adapted to be controlled by such an electrical conducting system.

A.further object of the invention is vthe provision of a relay system including a sensitive relay controlled by an' electrical conducting system of the above-mentioned type. The relay system may very well be utilized in a safety mechanism for controlling the supply of fuel to a main burner.

Another object of the invention is the provision of `a control system for burners in which a pilot burner llame not only operates to ignite the Afuel but thereafter co-operates with the main burner name to form part of a conductive path for a safety mechanism which is in control of the main burner.

Further objects of the invention will become apparent as the description thereof proceeds.

For a more complete understanding of the invention, reference may be had to the following description and accompanying single drawing which is a diagrammatic illustration of one embodiment of the invention. Y

Referring to the single figure of the drawing, an electrically operated iluid fuel supply controlling device in the form of an electrically driven horizontal rotary oil burner is indicated at I. A gas -pilot ame 2 issues from a burner tip 3 of insulated material which is connected to a gas supply pipe 4. The supply of gas tothe burner tip 3 is controlled by an electromagnetic valve 5 of that type which allows a minimum flow of gas when the electro-magnetic valve 5 is deenergized and allows a larger ow of gas, for expanding the pilot name 2 as shown by the dotted lines, upon energization of the electro-magnetic means which control the operation of valvel 5. Oil is supplied to the oil burner I by an oil supply pipe 6 in which there is an electro-magnetic valve 1 that completely discontinues the ow of oil to the oil burner I when deenergized and allows a predetermined flow thereto when energized.

The con'trol apparatus for the electro-magnetic valves 5 and 1 and the oil burner I includes a main switch herein shown as a thermostatic switch` generally indicated at 8. The thermostatic switch 8 is placed in the room or space to be heated and comprises a bimetallic element 9 which is secured at one end as shown at I0. The free end of bimetallic element 9 controls switch blades Il and I2. On a fall in the temperature to which thermostatic ele- Ament 9 responds, the free end thereof first moves switch blade into engagement with a contact I3 and thereafter moves switch blade I2 into engagement with a contact I4. When the temperature of the room or space to be heated rises, switch blade I2 first disengages contact I4 and thereafter switch blade II disengages contact I3.

The control system further includes rst and second electro-magnetic switching mechanisms generally indicated at l5 and I6. Electro-magnetic switching mechanism I5 comprises a relay coil I1 which, when energized, attracts an armature I8 that moves switch arms I9 and 26 respectively into engagement with contacts 2| and 22. When relay coil I1 is deenergized, armature I8 moves to its original position as shown in the drawing wherein switch arms I9 and 20 are out of engagement with contacts 2| and 22. Electro-magnetic switching mechanism I6 comprises a relay coil 23 which, upon energization, attracts an armature 24 that moves a switch arm 25 out of engagement with a contact 26 and into engagement with a contact 21. When relay coil 23 is deenergized, armature 24 moves to its original position as shown in the drawing wherein switch arm 25 is out of engagement with contact 21 and is in engagement with contact 26. yArmature 24 like- Wise operates a second switch arm 28 which vis normally in engagement with a contact 29 and is adapted to be moved into engagement withja contact 30 when armature 24 is attracted upon energization of relay coil 23. l

A heat operated delayed action switch comprises a bimetallic strip 3| which has one end secured'as shown at 32. An electrical heating element 33 is placed in cooperative relationship with bimetallic strip 3| and when energized heats bimetallic strip 3| causing the free end of the sameto engage a contact 34 after a time interval.

l The control system also includes safetyA mechanism comprising a thermal time switch generally indicated at 35 (known in the art as a warp switch or safety switch) and a combustion responsive circuit controlling mechanismgenerally indicated at 36. The safety switch comprises a pair of contacts A31 and 38 which are normally maintained in engagement by a bimetallic strip 39. A safety switch heating element 40 is adapted to heat bimetallic strip 39 when energized and, if this energization continues for a predetermined length of time, bimetallic strip 39 operates to allow contacts 31 and 38 to separate. These contacts will remain in their separated condition until manually reclosed after bimetallic strip 39 has cooled. The combustion responsive circuit controlling mechanism includes a sensitive relay herein shown as a grid controlled rectifier indicated at 4I and generally known as a grid glow tube. The grid glow tube 4| is provided with an anode 42, cathode 43, and grid 44. The grid 44 is connected to an electrode 45 which is out of the path of the flame produced by the oil burner I but which, under certain conditions, is electrically connected thereto by means of the expended pilot flame 2 as will be hereinafter more fully described. 'Ihe flame which issues from the oil burner I may contact certain portions thereof which in the normal construction of oil burners are conductors of electricity and the oil burner flame is thereby connected to ground. Even though the llame does not touch any part of the oil burner or the combustion chamber, it has been found that the charge from the grid 44 is dissipated by the oil burner llame. Therefore, the oil burner flame will be considered as grounded in the specification and claims.

Electrical power is supplied by means of line wires 46 and 41 and a combination step-up and step-down transformer having a medium voltage primary 48, a high voltage secondary 49 and a low voltage secondary 50. A condenser 5| is preferably connected in the control system in a manner and for reasons that will be later explained.

Operation The system is shown in its idle condition in the drawing with the main switch 8 in open circuit position, with pilot fiame 2 contracted, with the oil valve 1 closed and the oil burner idle. As the temperature surrounding bimetallic element 9 falls, switch blade I| will engage contact |3. No energizing circuits are thus established. As such temperature continues to fall, switch blade I2 will engage contact I4 to energize relay coil I1 and safety switchheating element 46 as follows: Low voltage secondary 50, wirej'52, contacts 38 and 31, wire 53, contact I3, switch blades II and I2, contact I4, wire 54, contact 26, switch arm 25 wire 55, safety switch heating element 40, wire 56,'rela'y coil Il, and wire 51 to low voltage secondary 56. Energization of relay coil I1 attracts armature I8 which in turn moves switch arms I9 and 26 into engagement with contacts 2| and 22. Engagement of switch arm I9 with contact 2| estab- 75 lishes a holding circuit for relay coil I1 and safety switch heating element 40 which is independent of switch blade I2, contact I4, contact 26, and switch arm 25. This holding circuit is as follows: low voltage secondary 50, wire 52,

contacts 31 and 38, wire 53, contact I3, switch blade II, thermostatic element 9, wire 58, contact 2|, switch arm I9, wire 59, wire 55, safety switch heating element 4I), wire 56, relay coil I1, and wire 51 to low voltage secondary 50. Engagement of switch arm 20 with contact 22 energizes oil burner motor I, electrical heating element 33 and electro-magnetic valve 5. The energizing circuit for oil burner I is as follows: line 46, wire 60, contact 22, switch arm 28, wire 6I, wire 62, oil burner I, wire 63, and wire 64 to line 41. The energizing circuit for electrical heating element 33 is as follows: line 46, wire 68, contact 22, switch arm 20, wire 6I, wire 65, wire 66, switch arm 28, contact 29, wire 61, electrical heating element 33, wire 68, wire 69, and wire 64 to line 41. The energizing circuit for electro-magneticV valve 5 is as follows: line 46, wire 69, contact 22, switch arm 20, wire 6I, wire 18, electro-magnetic Valve 5, andfwire 1I to line 41;

Electrical heating element 33 and safety switch heating element 40 are now being concurrently energized, the former by a medium voltage circuit and the latter by a low voltage circuit. The energization of electrical heating element 33 causes the free end of bimetallic element 3I to engage contact 34 to close an energizing circuit for oil valve 1 as follows: line 46, wire 60, contact 22, switch arm 20, wire 6I, wire 65, wire 12, contact 34, bimetallic strip 3I, wire 13, wire 14, electro-magnetic oil valve 1, wire 15, wire 69, and wire 64 to line 41. Energization of electro-magnetic oil valve 1 allows the flow of oil to oil burner I which has come up to running speed during the delay between its energization and the opening of oil valve 1. The previous energization of electro-magnetic gas valve 5 has allowed a larger flow of gas to the burner tip 3 which resulted in the enlargement of pilotv flame 2 as shown by the dotted lines. The oil issuing from oil burner I will normally become ignited by the expanded pilot flame 2. If such ignition does not take place, the continued heating of bimetallic strip.39 by safety switch heating element 40, will cause separation .of contacts 31 and 38 whereupon the system will be rendered inoperative until manual intervention.

Assuming that combustiondoes take place, an electrical circuit will be established from the grid 44 of grid glow tube 4I to ground as follows: grid 44, electrode 45, expanded pilot flame 2, the main oil burner flame 16, through the oil burner I to ground 11. This circuit allows the charge on grid 44 to be dissipated which results in the passage of current between the anode 42 and the cathode 43 of the grid glow tube. An energizing circuit for relay coil 23 isl thereby established and this energizing circuit is as follows: high voltage secondary 49, wire 18, anode 42, cathode 43, wire 19, relay coil 23,' wire 86, and wire 8I to high voltage secondary 48. The condenser 5I is connected in parallel with relay coil 23 by wires 82 and 83. The condenser 5I operates to smooth out the pulsations of direct current which flow to relay coil 23 through the grid glow tube 4I. Energization ofv relay coil 23 attracts armature 24 which in turn moves switch arm 25 out of engagement with contact 26 and into engagement with contact 21 and likewise moves switch arm 28 out of engagement with contact 29 and into engagement with contact 30. Separation or switch arm 25 from contact 26 interrupts the original energizing circuit for relay coil I1 and movement thereof into engagement with contact 21 establishes a shunt circuit, by means of wire 55 and a wire 84, around safety switch heating element 40 to operatively deenergize the same. Movement of switch arm 28 out of engagement with contact 29 deenergizes electrical heating element 33 and movement thereof into engagement with contact establishes a holding c1rcuit for oil valve 1, which is independent of contact 34 and bimetallic strip 3l. This holding circuit is as follows: line 46, wire 60, contact 22, switch arm 20, wire 6I, wire 65, wire 66, switch arm 28, contact 30, wire 85, wire 14, oil valve 1, wire 15, wire 69, and wire 64, to line 41.

The system is now operating normally and it will be noted that the expanded pilot flame 2 electrically connects electrode 45 with the main oil burner flame 16 so that it is unnecessary for the electrode 45 to protrude into the high temperature oil burner flame 16. When the room or` space to be heated reaches the desired temperature, thermostatic element 9 will disengage switch blade I2 from contact I4 and thereafter switch blade II from contact I3 whereupon relay coil I 1 will be deenergized. Such deenergization will move switch arm 20 from engagement with contact 22 whereupon oil burner I, electromagnetic gas valve 5 and electro-magnetic oil valve 1 will be deenergized. The oil burner flame 16 will be extinguished and the pilot flame 2 will be contracted whereupon the circuit from grid 44 to ground 11 will be interrupted. A new charge will collect on grid 44 and interrupt the ow of current between anode 42 and cathode 43 thereby deenergizing relay coil 234 returning the system to the condition and position shown in the drawing.

If there should be a failure of the electrical supply during operation, the parts will return to the position shown in the drawing and the apparatus will recycle to again attempt to establish combustion when power is resumed, if the main switch is closed.

If there should be a flame failure during normal operation, that is, if lthe flame should become extinguished or combustion should cease for any reason during normal operation after combustion had been initially successfully established, the circuit from grid 44 to ground 11 will be interrupted which will result in deenergization of relay coil 23 as heretofore described.

Deenergization of relay coil 23 will allow switch arm 25 to move from engagementwith contact 21 thereby removing the shunt around safety switch yheating element 40.. Bimetallic strip 39 will therefore become heated until, at the end of a predetermined time, contacts 31 and 38 will separate to render the system inoperative until manual intervention.

' Fromthe foregoing description, it will be apparent that this invention provi des a novel electrical conducting system which includes an elec-` trode that is electrically connected to a main high temperature oil burner flame by means of a lower temperature gas name. It will also be apparent that this invention provides a novel control circuit including such an electrical conducting control system and that the low temperature gas ame also acts as the ignition means for the main flame.

Y While a specific embodiment of the invention has been herein described it will be readily appreciated that various modifications could be made therein.

I claim as my invention;

1. A system of the class described, comprising, in combination, an electrically operated fluid fuel supply controlling device for producing a high temperature flame, a sensitive relay, an energizing circuit for the fuel supply controlling deiice controlled by said relay, means for producing a low temperature name intersecting said high temperature flame, and acircuit for operatively energizing said relay, said circuit including the low temperature flame and high temperature flame in series as part ofits conducting path.

2..A system of the class described, comprising,` in combination, an electrically operated fluid fuel supply controlling device for producing a high temperature flame, a main switch for initiating operation of the same, a fluid fuel burner producing a relatively low temperature flame directed into the path of the fuel supplied by said device for igniting such fuel, means for rendering the fuel supply controlling device inoperative if combustion is not successfully established within a predetermined time after closure of the main switch, and an electrical circuit operable when completed and energized in response to the establishment of combustion within said predetermined time to maintain operation of the fuel supply controlling device,'said circuit including in series the main flame and the ignition flame as electrical conductors.

' 3. An electrical controlling system, comprising, in combination, a grid controlled electrical discharge device for controlling energlzation of a load circuit, means for producing a high temperature flame, means for producing a low temperature ame intersecting the high temperature flame, an electrode positioned in the low temperature flame and a grid controlling circuit comprising said electrode, high temperature flame and low temperature flame in series whereby the grid circuit will be completed when both said flames are burning and in contact with each other.

4. An electrical controlling system of the class described, comprising, in combination, a grid glow tube comprising an anode, a cathode, and a grid, a load circuit connected to the anode and cathode, means for producing a high temperature flame, means for producing a low temperature flame intersecting the high temperature flame, an electrode positioned in the low temperature llame and a grid controlling circuit including, in series, said grid, electrode, high temperature flame, and low temperature flame whereby the grid charge is dissipated when both flames are present and in contact with each other thereby completing the load circuit through the anode and cathode of the grid glow tube.

5. A system ofthe class described, comprising, in combination, a main fluid fuel burner, means for producing a low temperature iiame intersecting the ame-of the main burner, and a safety mechanism forl preventing operation thereof if ame is not being produced thereby, said safety .mechanism Acomprising a`sensitive electrical device, and means forming a circuit therefor including a conductor connected to the sensitive electrical device and terminating insaid intersecting low temperature ame Whereby said circuit is energized only when both 'flames are present and in 'contact with each other'.v

6. A system of the class described, comprising, in combination, an electrically operated fluid fuel supply controlling device, a main switch for initiating operation thereof when closed, an auxiliary iiuid fuel burner producing a low temperature flame for igniting the fuel supplied by the fuel supply controlling device, a current responsive device energized upon closure of the main switch and operable to terminate operation of the fuel supply controlling device if such energization continues for. a predetermined length of time, and means operable upon the establishment of combustion to operatively deenergize said current responsive device, said means comprising a grid controlled electrical discharge device and a grid circuit therefor including in series a conductor removed from the path of the main flame and in contact with the flame of the ignition burner, whereby the ignition burner completes a circuit between said conductor and the main flame if combustion is established.

7. In an electrical control circuit'having an air gap normally interruptingthe same, means for producinga high temperature flame in electrical engagement with-one side of the gap, and means for producing a lower temperature flame intersecting said high temperature flame and in electrical engagement with the other side of the gap, said intersecting flames providing a series connected current path closing the aforementioned gap in said electrical control circuit.

8. In an electrical circuit having spaced conductors forming an air gap normally interrupting the flow of current through the same and provided with an electrode on one side thereof, means for producing a high temperature flame in electrical engagement with the other side of said gap, and means for producing a lower temperature flame intersecting said high temperature flame, said eleectrode being located in the path of said low temperature ame and said intersecting nigh and low temperature flames providing a series connected current path closing the aforementioned gap in said electrical circuit. v f

9. In combination, means for providing a high temperature flame, means for producing a low temperature ame intersecting the high temperature flame, anV electrode positioned in :the low temperature flame, and means forming an electrical circuit including said electrode and high and low temperature llames in series, which is completed only when both flames are present and in contact with each other. i

10. A safetyf'mechanism in combination with a high temperature ame producing means, and ,means for producing a low temperature ame intersecting the high temperature flame, comprising a sensitive relay in control of the high temperature flame producing means, and means forming an electrical circuit in control thereof including said high and low temperature flames in series, whereby said circuit .is closed only when both ames are present and in contact with each other. l

11. A safety mechanism in combination with a high temperature flame producing meanaand means for producing a low temperature flame intersecting the path of the high temperature I ame to ignite the same, comprising in combination, an electrode located in the path of the low temperature iiame but removed from the path of the high temperature flame, a sensitive relay controlling the operation of the high temperature ame producing means, and means 'forming a circuit in control of the relay including said electrode and said high and low temperature iiames in series, whereby said circuit is interrupted in the absence of either the high temperature or low temperature ame.

12. In combination with means for producing a high temperature iiame and means for producing a 10W temperature flame intersecting the high temperature llame, an electrical circuit comprising spaced conductors electrically connected by said iiames in series whereby said circuit is closed only When both flames are present and in contact with each other. 

